Field of the Invention
The present invention relates to a sewing machine, and more particularly to a sewing machine with a threading and air supply selecting device.
Description of the Prior Art
Sewing machines have a variety forms, for example, overlock sewing machine is provided with a main shaft which is used to drive the needle and a plurality of thread wipers. In order for easy and quick threading of the upper thread hook, many automatic threading devices have been invented. For instance, Taiwan Patent No. 46553 discloses an automatic needle threading device which threads the needle by a jet of air. Taiwan Patent Nos. 193730 and 1402391 also disclose a device for threading the thread wiper by a jet of air, wherein the air introduction system is a retractile pipe. The movement of the air source or the main shaft can not be effectively controlled during the movement of the air introduction system, which results in inconvenience in air supplying, and the ON and OFF of the drive force source cannot be effectively controlled, leading to safety concerns.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.